To make driving safer, modern cars are equipped with various electronic driving-aid devices, such as an ABS (Anti Block System—to prevent the wheels blocking when braking), ESP (Electronic Stability Program—to control vehicle stability), ASP (Anti Skid Program—to prevent the drive wheels from skidding), and an electronic suspension control system (to adjust mechanical response of the suspensions to external stress).
Some cars are also equipped with a selection device which allows the driver to select and communicate a given dynamic vehicle performance to a central control unit, which accordingly adjusts the operating parameters of the electronic driving-aid devices to match dynamic vehicle performance as closely as possible to the drivers choice. By means of the selection device, the driver is able to adapt the dynamic performance of the vehicle to his or her personal driving style and to different weather and road conditions, thus greatly improving driving safety, particularly in difficult weather and road conditions, such as heavy rainfall, snow or ice.
One example of such a selection device is described in Patent Application WO2004087484A1, in which the selection device comprises a switch built into the steering wheel, and which can be turned to five different settings, each corresponding to a respective dynamic vehicle performance.
Very often, however, drivers tend to miscalculate—in particular, overestimate—their driving skill and, more importantly, their psychophysical condition, with the result that driver-selected dynamic vehicle performance simply reflects the driver's wish, as opposed to the driver's actual psychophysical condition and proficiency, and so amounts to an impairment in driving safety, in the sense of the driver being in control of a vehicle that does not respond adequately to his or her actual psychophysical condition.
The problem of correct psychophysical evaluation of the driver is widely covered in technical literature, which proposes numerous ways of recording psychophysical parameters to evaluate the driver's psychophysical condition, and of employing the evaluation to emit warning signals, to keep the driver alert by acting on internal vehicle systems, and/or to stop the vehicle in the event of the driver losing consciousness. By way of example, the following are just a few of the documents relating to correct psychophysical evaluation of the driver.
Patent Application US2005015016A1 describes a method of determining a driver's mental state and stress by analysing the driver's brain waves.
Patent Application US2003146841A1 describes a method of determining driver stress using various physiological sensors, so appropriate action can be taken if the stress level exceeds a predetermined alarm threshold.
Patent Application GB2394288A describes a steering wheel equipped with sensors for detecting various physical characteristics of the driver, by which to evaluate the driver's psychophysical condition.
Patent Application WO02096694A1 describes monitoring a driver's psychophysical condition, so as to intervene accordingly on various vehicle control units to safeguard the driver. More specifically, in the event of the driver losing consciousness, the vehicle is kept on the right path by acting on the electric power steering control, and is slowed down till it stops, by acting on the cruising control.
U.S. Pat. No. 5,942,979A1 describes monitoring a driver's physical condition. If an emergency situation is detected, the driver is alerted by visual and acoustic signals, and the vehicle can be stopped automatically by acting on the brake and/or injection system.
All the driver psychophysical evaluation solutions described in literature, however, relate to determining and controlling imminent-hazard situations, in which the driver is drowsy or unconscious, and none as yet have investigated the possibility of using physiological parameters to enhance driving pleasure and reduce driving fatigue.
Patent Application WO2007090896A1 describes a method of controlling a driver-operated vehicle, which comprises the steps of: recording a number of psychophysical driver parameters by means of respective biometric and psychometric sensors; evaluating the driver's psychophysical condition as a function of the psychophysical parameters recorded by the biometric and psychometric sensors; and accordingly adjusting the dynamic performance of the vehicle to the driver's psychophysical condition. Evaluating the driver's psychophysical condition as a function of the psychophysical parameters recorded by the biometric sensors, however, is extremely complicated, on account of the difficulty in determining a precise connection between the psychophysical parameters recorded by the biometric and psychometric sensors and the actual psychophysical condition of the driver, and is complicated even further by the wide range of parameter values assumed from one person to another. For example, the threshold value indicating a fast heart rate varies widely from one person to another (typically, the better shape a person is in, the lower the heart rate is at rest).